c. 1300, "booth or shed for trade or work," perhaps from Old English scoppa, a rare word of uncertain meaning, apparently related to scypen "cowshed," from Proto-Germanic *skoppan "small additional structure" (source also of Old High German scopf "building without walls, porch," German dialectal Scopf "porch, cart-shed, barn," German Schuppen "a shed"), from root *skupp-. Or the Middle English word was acquired from Old French eschoppe "booth, stall" (Modern French échoppe), which is a Germanic loan-word from the same root.
Meaning "building or room set aside for sale of merchandise" is from mid-14c. Meaning "schoolroom equipped for teaching vocational arts" is from 1914, American English. Sense of "matters pertaining to one's trade" is from 1814 (as in talk shop (v.), 1860).
c. 1300 (late 13c. as a surname), "one who has charge of some person or thing, warden," agent noun from keep (v.). Sense of "one who carries on some business" is from mid-15c. Sporting sense (originally cricket) is from 1744. Meaning "something (or someone) worth keeping" is attested by 1999. Brother's keeper is from Genesis iv.9.